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authorVaibhav Jain <vaibhav@linux.vnet.ibm.com>2017-05-19 22:18:55 +0530
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2017-05-31 13:04:54 +0200
commitda96aea0ed177105cb13ee83b328f6c61e061d3f (patch)
treea0f140bd6f0d3c6853e2b2f4b7390521d5083eef /drivers/rtc
parent6dc1cf6f932bb0ea4d8f5e913a0a401ecacd2f03 (diff)
rtc: interface: Validate alarm-time before handling rollover
In function __rtc_read_alarm() its possible for an alarm time-stamp to be invalid even after replacing missing components with current time-stamp. The condition 'alarm->time.tm_year < 70' will trigger this case and will cause the call to 'rtc_tm_to_time64(&alarm->time)' return a negative value for variable t_alm. While handling alarm rollover this negative t_alm (assumed to seconds offset from '1970-01-01 00:00:00') is converted back to rtc_time via rtc_time64_to_tm() which results in this error log with seemingly garbage values: "rtc rtc0: invalid alarm value: -2-1--1041528741 2005511117:71582844:32" This error was generated when the rtc driver (rtc-opal in this case) returned an alarm time-stamp of '00-00-00 00:00:00' to indicate that the alarm is disabled. Though I have submitted a separate fix for the rtc-opal driver, this issue may potentially impact other existing/future rtc drivers. To fix this issue the patch validates the alarm time-stamp just after filling up the missing datetime components and if rtc_valid_tm() still reports it to be invalid then bails out of the function without handling the rollover. Reported-by: Steve Best <sbest@redhat.com> Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/interface.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index fc0fa7577636..8cec9a02c0b8 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -227,6 +227,13 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
missing = year;
}
+ /* Can't proceed if alarm is still invalid after replacing
+ * missing fields.
+ */
+ err = rtc_valid_tm(&alarm->time);
+ if (err)
+ goto done;
+
/* with luck, no rollover is needed */
t_now = rtc_tm_to_time64(&now);
t_alm = rtc_tm_to_time64(&alarm->time);
@@ -278,9 +285,9 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
dev_warn(&rtc->dev, "alarm rollover not handled\n");
}
-done:
err = rtc_valid_tm(&alarm->time);
+done:
if (err) {
dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,